The promotion of composting as an option for sustainable waste management has
raised concerns regarding public health impacts of exposures to potentially
hazardous bioaerosols. Recent source term experiments show that bioaerosol
emissions are episodic and that peak emissions are related to compost agitation.
The Environment Agency requires risk assessments for facilities that have
sensitive receptors within 250m of their boundary. In order to improve current
risk assessment methodologies, improved predictions of bioaerosol dispersal are
required. Dispersion modelling has been successfully used to determine
dispersion of odours from waste management. In this paper, bioaerosol
concentration data measured at a composting facility is analysed in an ongoing
series of model experiments, using the ADMS air dispersion model. Initial
modelling results reveal that the concentrations of bioaerosols decrease rapidly
with distance from the site, although under certain circumstances, it is
possible that higher concentrations may still be present at 200m from the site
boundary. However, dispersion models are not yet able to take into account all
the properties of bioaerosols, in particular, their viability and their ability
to aggregate and form clumps, which will affect the rate of dispersal. A series
of experiments were designed to examine how the options within dispersion model
affect the dispersion of bioaerosols and under which circumstances high
concentrations may disperse to sensitive receptors. The results will be compared
with bioaerosol measurements taken downwind of a composting facility, to
determine the accuracy of the model predictions. This is the first stage in an
attempt to design a best practice method for modelling bioaerosols.